Treatment of cotton



produced wholly or in Patented Dec. 7, 1943 UNETEDI ST i S H TREATMENT OF COTTON Florence E.

Hooper, Yonkers, N. Y., assignor to The Chemical Foundation, Incorporated, a corporation of Delaware No Drawing. Application January 6, 1940, I

Serial No. 312,687

11 Claims. (01.260 21?) This invention relates to the treatment of cotton, more particularly to a novel bacterial treatment of cotton as a result of which the cotton is improved for subsequent treatment.

In the past it has been observed that rayons,

part from cotton, sometimes contain specific inhomogeneities which seriously detract from the value of the product. For example, many times in a given production of cuprammonium silk it will be found that the extruded thread has segregated small areas which are non-receptive to a dye. Such a dinerential dyeing ruins the thread for many purposes.

It has been ascertained that this and kindred difiiculties may be largely due to the cuticle of the cotton fiber which is not removed during the purification. While the cotton fiber consists essentially of ellipsoidal, crystalline cellulose particles dispersed in a continuous phase of a cementing material, it does also contain, in the limiting membrane, a non-cellulosic material of a waxy nature. This material, sometimes referred to in the literature as cutocellulose, is very small in amount but is of such a resistant or refractory character that in many circumstances it passes unchanged through the purification treatments and appears in the final product. Its presence is distinctly disadvantageous not only because it is a positive inhomogeneity and may well spoil a dyed thread or sheet, but also because it appears to inhibit the dispersion of the cellulose particles in dispersing solutions such as cuprammonium hydroxide.

While this undesired constituent could be removed by decomposing it with chemical reagents,

a drawback of such a method, however, would be a concomitant and undesired degradation of the other constituents of the fiber. The ideal method of removal of this cuticle material is one which is directly selective and which removes such material without undesired change or modification of the other components of the cotton fiber.

After extensive experimentation, it has been found that this undesired non-cellulosic waxy constituent may selectively be removed by a controlled bacterial treatment and without any sub.- stantial action on the other constituents of the fiber. With such a treatment, an improved raw material for rayon production is made available. Furthermore, another important and advantageous concomitant of the novel treatment is that fibers so treated disperse much more readily anduniformly in typical dispersing solutions than do untreated fibers.

Preliminary investigations conducted to establish the best commercial method conclusively show that certain aerobic cellulose-decomposing bacteria from the soil, when properly cultured onraw cotton, act in two more or less definite sequential stages. The bacteria first act on the cuticle of the cotton to directly decompose it, and then the bacteria more slowly disintegrate the fiber. itself. It is particularly to be observed, therefore, that the present invention involves not only a specific bacterial action but that it also involves a distinct specificity with respect to the time of the action. For example, cellulosic-decomposing bacteria when cultured on raw cotton in the presence of inorganic salts and at a temperature of 25 to 30 C. first act on the cuticle. If such inoculated fibers are removed from the culture at the end of about five days and are washed, it is found that the cuticle is completely removed but the fibers are otherwise intact. It is particularly interesting to observe that the viscosity of the treated fibers when dispersed in cuprammonium hydroxide re mains unchanged. The fibers treated by this bacterial method, however, disperse much more rapidly and uniformly in cuprammonium hydroxide and Xanthate solutions than do the un treated fibers.

In the course of experimentation, it was found that a large number of cellulose-decomposing bacteria are operative in the process. These bacteria, which are notably diflicult of classification, include members of the cellulose-decomposing genera of the Pseudomcndaceae, namely, Cellvibrio and Cellialliculo, as well as members of the genus Bacteriaceae, as for example Cellulornonas.

In carrying out the process, a quantity of cotton is placed in a nutrient salt solution, then sterilized, as by autoclaving at elevated temperatures, and inoculated with a pure culture of the micro-organism. At the end of the period required to remove the cuticle the bacteria are killed, as for example by autoclaving or by heating for 10 mately C. The treated cotton may then be washed, fitlered and air-dried. While it has been determined that a definite time period must be allowed for the selective action of the bacteria on the cuticle, there is, of course, no abrupt or sharp demarcation of the cessation of the action'on the cuticle and the institution of bac-' terial action on the fiber per'se. It has been found, as an operative fact, that a period of five minutes at a temperature of approxi-' days is amply sufficient to insure the destruction of the cuticle and without any substantial action on the other constituents.

In commercial production the bacterial treatment may be conducted at any stage which most readily conforms to the requirement of a particular plant or process. Other things being equal, it is preferable to effect the selective removal of the undesired cuticle-like constituents of the raw cotton prior to subsequent treatments, such as treatments with caustic for the formation of alkali cellulose. In any event, due to the noted fact that the treatment does improve the dispersibility of the cellulose of the fiber, it is pref monium. hydroxide to form a spinning solution- With such a treatment it is found that the cellulose dispersed very readily in the cuprammonium hydroxide and theregenerated fiber or sheet produced is characterized by a greatly increased uni formity in dye acceptance.

Similarly, improved material for acetate silks" may be produced by subjecting the cellulosic' starting material, such as cotton linters; to the improved selective bacterial action. Thereafter the fibers may be treated with" the known mixture of acetic anhydride, glacial acetic acid andsu-l phur dioxide. Floccules produced by the addition of water may be dissolved in a'cetoneito form a spinning solution and the solution is extrudedinto the desired form in the known manner.

In the production of viscose rayons it is pref-- erable to first subject any cuticle-containingraw material to the described bacterial action prior to treatment with the 18% caustic solution, 1. e., prior to the formation of the alkali cellulose. It has been found, as noted, that this bacteria-lpretreatment not only insures the production of an improved fiber but also-greatly facilitates'the dispersion of the alkali cellulose in'the xanthat'e solution.

It will thus be appreciated that the method herein described is available for improvement. in any technological field where the cotton fiber:

is used in the original or the regenerated, reconstituted or derivative form. As noted'hereinbefore, selective removal of the cuticle insures a more uniform dyeing. due to the fact that the waxy dye-resistant material is removed. While the process is particularly valuable for the treat-- ment of cotton fibers entering into rayon production, it is also available for the treatmentof'cotton, as such, which is subsequently utilized in the production of cotton fabrics. It will: be understood, therefore, that the invention resides.- in the broad concept of the. selective bacteriah removal of those constituents which are comprised in the cuticle phase of the in other cellulosicproducts in which a chemical phase equivalent to the=cuticle of with advantage in the production of viscoserayon, acetate rayon, cellulose ethers, suchas ethyl cellulose, and esters, such as gun cotton cellulose:

nitrate and the like.

cottonfiber and the cotton fiber' is involved. The new method may thusvbeused' I claim:

1. As a new product, cotton fiber, characterized by a ready dispersibility in cellulose dispersion agents, which has been subjected to the action of aerobic cellulose-decomposing bacteria for a time sufficiently prolonged to decompose the cuticle but without subtsantial decomposition of the cellulose.

2. A rayon, characterized by a highly uniform dye acceptability, produced at least in part from cotton fibers which have been subjected for a limited period of time to the action of aerobic cellulose-decomposing. bacteria.

' 3. A ra-yon,,- characterized by a highly uniform dye acceptability produced at least in part from cotton fibers which have been subjected for a limited period of time to the action of a Pseudomond-aceae to decompose the cuticle of the fibers without substantial decomposition of the cellulose.

4: A method of producing'dispersions of cotton which comprises subjecting the cotton. to the ac-- tion of an aerobic cellulose-decomposing bac? teria for a period of approximately five days; treating the cotton to inactivate and remove the bacteria, and subsequently dispersing the treated materialin a cellulose-dispersing solution.

5. A method of' producing readily dispersible alkali cellulose which comprises treating cotton with an aerobic cellulose-decomposing bacteria fora periodof' time suificiently prolonged to d estroy the cuticleof the cotton, removingthe'bacteria and its decomposition productsand treating the cotton with sodium hydroxide of substantial 1y 18% concentration. I

63 'A method of producing readily dispersible alkali cellulose which comprises treating cuticlecontaining cellulose with anaerobic cellulose decomposing bacteria fora period of time sufilclent-- lyprolonged to destroy the cuticle but without any substantial decomposition of the cellulose, removing the bacteria an'dits decomposition prod-- ucts and treating the cellulosic material wi'th so--' dium hydroxide of substantiatlly' 18% concentration.

'7'. A method of purifying cottonwhich com prises inoculating cotton in the: pres'ence of a-hu trientsaltsolution witha culture of a Pseudo mondaceae, maintaining the: solutionat a t'eri'1-- perature of the: order of 25 C. for a: period an proximatings' five: days, inactivatingthe bacteria,

and. removing the bacteria and its decomposi tion products from the cottona 8. A method of purifying cotton which com prises inoculating; cotton in' the-presenceof a nutrient salt-solution with a culture of a; cellu'-' lose-decomposing. Bacteriaceae, maintaining? the solution at a temperature of the; order: of- 25 6. for a period approximatin five days; inactivating the bacteria, andaremoving the bacteria and; its decomposition products from: the cotton.

9. A method of purifying; cotton which coinprises sterilizing; cotton in the presence of a nutrient salt solution, inoculating the cotton-with a culture of Cellvibrio, maintaining the. mass at a temperature of substantially 25 0.. for a pe'-' riod of from: four. tosixdays, heating. the mass? to axtemperature sufficiently. high: to inactivate theb'acteriaand: separating the bacteria and itsdecomposition: products from the cotton.

10; A method: of purifying cottoniwhich com prises sterilizing. cotton in the presence of a nutrient saltsolution;.inoculatingthe; cotton with; a culture of Cellfa-lliculo;. maintaining the: mass at a temperature of substantially 25 C. for a period of from four to six days, heating the mass to a temperature sufiiciently high to inactivate the bacteria and separating the bacteria and its decomposition products from the cotton.

11. A method of purifying cotton which comprises sterilizing cotton in the presence of a nutrient salt solution, inoculating the cotton with a culture of Cellulomonas, maintaining the mass at a temperature of substantially 25 C. for a period of from four to six days, heating the mass to a temperature sufiiciently high to inactivate the bacteria and separating the bacteria and v its decomposition products from the cotton.

FLORENCE E. HOOPER. 

